DakotaFleck
Posts: 4
Joined: Thu Apr 12, 2018 5:45 pm

Potential Car Project

Thu Mar 26, 2020 4:28 am

Hello all! I have an idea for a car project and need some help in the planning portion. I did some digging and I really am not a fan of how other people made their radio from rpi so I have come up with a rough plan. Essentially I wish to create a touchscreen radio with an rpi 4(would have to buy) which can act as a radio and as a real time data monitoring system. Here's the simplest way I can explain:

- Overall power would come from 12v car battery
- Speaker power would come from factory wiring harness
- Speaker audio would come from the rpi connected to an amp(via aux to rca) connected to the speakers
- Rpi power would come from accessory port(car charger)
- Touchscreen power would piggyback off the rpi via an adapter board supplied with the screen
- Real time data monitoring through OBD2 to bluetooth

Now. My biggest concern is would adding this to everything else the battery supplies power to overload the system and cause electrical failures?(ie lights not working properly).The only thing i think would help is adding load equalizers but im not sure if that will do the trick.

Also is there a way to run both CarPi and OBDPi together? Not at the same time but sort of like apps on phones. Tapping on an icon would start the program(preferably a fast boot and not an insanely slow one). Then pressing an "x" or "close" button would go back to a main menu where I could switch to the other program.

Any help is appreciated. Thank you in advance!!

deepo
Posts: 450
Joined: Sun Dec 30, 2018 8:36 pm
Location: Denmark

Re: Potential Car Project

Thu Mar 26, 2020 3:52 pm

Powering a RPi from the car battery could empty the battery, so don't have it running all the time.
Other than that I don't see a problem adding a RPi to the car, provided you supply it through a fuse.

You mention: "Real time data monitoring through OBD2 to bluetooth"
If you're not going to use the OBD2 data in your solution then a simple OBD2 Bluetooth plug would be way easier to buy and install, compared to write software that does that task.

What's wrong with the other RPi car computer solutions you have looked at?
And which have you looked at?

/Mogens

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Imperf3kt
Posts: 3382
Joined: Tue Jun 20, 2017 12:16 am
Location: Australia

Re: Potential Car Project

Thu Mar 26, 2020 9:10 pm

- Rpi power would come from accessory port(car charger)
You should not do this. Having the power come from the accessory power means your Pi will abruptly lose power every time you turn your car off. This is not good for it.

You need to find a way to signal a start up / shut down based on the accessory power and power the Pi directly via a switching regulator connected to the battery via an appropriately rated fuse.
55:55:44:44:4C
52:4C:52:42:41

skrimo
Posts: 4
Joined: Sat Jul 06, 2019 7:25 am

Re: Potential Car Project

Tue Mar 31, 2020 11:22 am

thats really not that hard to do.

Im using OpenautoPro OS (www.bluewavestudio.io). it is based on raspbian os, it works on pi3b, pi3b+ and pi4.
it has:
- built in music player and internet radio (if you have internet access via phone tethering, wifi, gps hat)
- rear view camera and/or dashcam (you need cameras offcourse)
- AndroidAuto for navigation
- they are working hard on OBD2 live data management

for now, you can use "Torque AndroidAuto app" and have it displayed in the AndroidAuto enviroment

basically it offers everything you want.

it does cost 28usd , but for that money you get alot of fun and lifetime free updates.


I have it in my car for roughtly 1.5 years now and really loving it.
Im also using one of the many save shutdown solution on ther forum (one of them is mine).
for basic save shutdown you really only need:
1x 12V timer delay relay,
1x 12V 5-pin automotive relay
2x 1N5408 diode
some power wires and gpio jumper wires
and a phyton script that is monitoring gpio17 (or any choosen gpio)

this is what Im using
power1.jpg
power1.jpg (97.07 KiB) Viewed 105 times

and offcourse you will need:
- raspberry pi,
- touchscreen
- 12V to 5V buck converter
- powered usb hub (raspberry pi wont be able to power all the pheripherals)
- usb sound card
- usb bluetooth dongle if you want handsfree phone calls (based on CSR chip, becouse built in broadcom chip does NOT support phone calls forwarding)

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thagrol
Posts: 2418
Joined: Fri Jan 13, 2012 4:41 pm
Location: Darkest Somerset, UK
Contact: Website

Re: Potential Car Project

Tue Mar 31, 2020 3:21 pm

Imperf3kt wrote:
Thu Mar 26, 2020 9:10 pm
- Rpi power would come from accessory port(car charger)
You should not do this. Having the power come from the accessory power means your Pi will abruptly lose power every time you turn your car off. This is not good for it.
I've been doing that quite happily for several years without SD card corruption. However I took the step of making sure that the entire thing boots up with all partitions mounted read only.

It's not just when you turn the car off. Accessory power gets cut when you activate the starter motor too. The sequence as you turn the key goes something like this:
  1. All off
  2. Accessory only.
  3. Accessory and ignition
  4. Ignition and starter
  5. Back to accessory and ignition
  6. Accessory only.
  7. All off
If you want to avoid power loss and a reboot when the engine is started you'll need to allow for that in your power supply design. Even then you may see a brown out on the Pi's supply as starting the engine takes a lot of current.
Attempts to contact me outside of these forums will be ignored unless signed in triplicate, sent in, sent back, queried, lost, found, subjected to public enquiry, lost again, and finally buried in soft peat for three months and recycled as firelighters

[email protected]
Posts: 39
Joined: Thu May 31, 2012 8:04 pm

Re: Potential Car Project

Tue Mar 31, 2020 5:05 pm

Hey @skrimo, I have bought OpenAutoPro on my pi and touchscreen. But I have had a few hassles with it.

Could you please contact me off list to discuss, please......

[email protected]

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